Photoshop is great, but if money is tight, try Gimp. Honestly, this is the only real way to edit the sprite sheet, aside from, say, MSPAINT or some other sub-par (par?) editor lol.
Yes by navigator I meant Internet navigator (browser).
They're smaller due to the fact that you have to render them client-side, not raster images. I get what you mean but people are still using IE9.
Seems pretty widely available, we should contact reddit about that. It'd be great to test out, considerably lowering page sizes and load times.
You're welcome! Might I suggest http://www.codecademy.com/ That site helped me learn to grasp CSS tremendously, along with a few other languages ;)
There are other resources as well. When I get home, I'll try and compile a more intriguing list for ya!